Correlation between the Degree of Alkylation and Tribological Properties of Amino-PEG2-amine-Based Organic Friction Modifiers

Abstract

The pursuit of fuel economy in the automobile industry continuously drives the development of low-viscosity lubricants. The present article reports the application of amino-PEG2-amine and its two N,N′-n-octyl-substituted derivatives as friction modifiers, which play a key role in low-viscosity lubricants. The diaminebased friction modifiers with multiple oxygen and nitrogen binding sites exhibit varying tribological properties relying on the degree of alkylation. Amino-PEG2amine exhibits relatively superior wear resistance versus base oil, while the disubstituted secondary diamine turns out to be optimal in friction reduction. Detailed investigations at elevated temperatures demonstrate that the secondary diamine outperforms the two other diamines in friction reduction and maintains stable tribological properties over the whole temperature range. Molecular structure analysis and electron density calculation suggest that the effect of alkylation degree on electron density and steric hindrance has a direct impact on surface adsorption, leading to diverse tribological performance.

Multifunctional Tunable Polymethacrylates for Enhanced Shear Stability and Wear Prevention

“…Boron- and nitrogen-containing compounds such as amines, amides, and imides are thought to be the most promising organic FMs. − We applied this knowledge to build polymers with controlled molecular weights, which contain nitrogen, oxygen, and boron as potential polar surface anchors. In order to probe the validity of the approach, the friction and wear were evaluated using the apparatus, as described in the Experimental Section.…”

Alkyl-Ethylene Amines as Effective Organic Friction Modifiers for the Boundary Lubrication Regime

“…The alkyl-ethylene amines reported in this research were synthesized according to our previously reported procedure. 26 This series of amine-based compounds contained different numbers of nitrogen atoms and molecular configurations. Specifically, the number of nitrogen atoms of TEA and TTEA (N = 4) is more than that of DEA (N = 3); meanwhile, the nitrogen atoms are arranged in a regular linear permutation for DEA and TTEA, while a clawlike three-dimensional structure was observed in TEA as shown in Scheme 1.…”

“…The alkyl-ethylene amines reported in this research were synthesized according to our previously reported procedure . This series of amine-based compounds contained different numbers of nitrogen atoms and molecular configurations.…”

“…Our previous studies have demonstrated that long-chain alkyl substitution can significantly improve the friction reduction performance of amine-PEG-amine, and the disubstituted secondary diamine turned out to be optimal in friction reduction. 26 Therefore, three ethylene amines with varying molecular configurations and nitrogen-atom numbers were alkylated to obtain a new breed of compounds as FMs containing both secondary and tertiary amine groups. After that, friction and wear behaviors were systematically investigated to discover the correlation between the molecular structure and tribological performance.…”

“…Therefore, the ethylene amine with multiple nitrogen atoms is supposed to be used as a precursor for FMs to facilitate the formation of physical adsorption films. Our previous studies have demonstrated that long-chain alkyl substitution can significantly improve the friction reduction performance of amine-PEG-amine, and the disubstituted secondary diamine turned out to be optimal in friction reduction . Therefore, three ethylene amines with varying molecular configurations and nitrogen-atom numbers were alkylated to obtain a new breed of compounds as FMs containing both secondary and tertiary amine groups.…”